South China Sea Annual Meeting 2023 (SCSAM)

38 / 2023-07-24 15:08:01

Characteristics and Mechanisms of Typhoon-Induced Decomposition of Organic Matter and Its Implication for Climate Change

Typhoons; decomposition; phytoplankton blooms; organic matter;

Typhoons are extreme weather events that can not only affect marine dynamics, but also change marine biogeochemistry, significantly impacting the marine eco-environment and climate. Recently, we reported that decomposition (as a carbon source) of organic matter (OM) is the dominant process in coastal waters after typhoons based on field observation, which is contrary to phytoplankton blooms (as a carbon sink) in previous studies using satellite remote sensing data. The characteristics and mechanisms of typhoon-induced decomposition of organic matter can significantly affect the global carbon and nitrogen cycles, and the efficiency of the biological pump and global climate change. Our studies based on several typhoon field observations showed that not all typhoons can trigger phytoplankton blooms in the oceans, which mainly depends on the supply of nutrients after typhoons. However, a positive apparent oxygen utilization in the coastal waters, suggested that the decomposition of OM was the dominant biogeochemical process regardless of whether phytoplankton blooms occurred after the typhoon. More importantly, we found that typhoon-induced decomposition might be dominated by POM, which is not conducive to the storage of OM in sediments. It means that the capacity of sediments as a carbon sink will be weakened under global warming (with increasing typhoon events).